What Is This?

[Tywais]

I was outside the office and felt something touching my neck and thought it was an insect. However when I stepped away saw it was a long stem from the below plant. A couple of minutes later, my neck was itching like crazy and a long welt where the plant touched me. Any idea what it is and if there are toxins in it to cause such a quick significant reaction? Made me think of poison ivy, but was told it was not poisonous. Put some Tiger Balm on it and it feels better now but still a large welt there and very red.

[Phil Conners]

Probably more likely to be a red ant crawling on it which jumped onto you when you touched it. The big red ants often live in trees and get really aggressive when you get anywhere near them.

[sbk]

Actually, there a few vines that cause welts, usually because the bark is quite rough and sandpapery, not because of any poisonous properties. Check out the bark on the vine to see. Otherwise, it could be an ant.

I wouldn't worry about it too much, I garden alot as well as visit the inlaws coconut plantations and (barring an allergic reaction) have never encountered any plant terribly poisonous. Just with nasty thorns

[Tywais]

Probably more likely to be a red ant crawling on it which jumped onto you when you touched it. The big red ants often live in trees and get really aggressive when you get anywhere near them.

No ants, and I know which ones you mean - have bunches of them at my house and know how they feel. In this case the welt was about 3 cm long and thin just like the plant.

Just talked with a Thai here and she says it has very fine hairs, like needles that scrape the skin and some come off and stick in the skin. Nearly an hour later and the welt is still there but not as big and the itching finally has stopped. Perhaps my skin is just hyper-sensitive to it because she was rubbing her finger along it to show me the roughness. I took her word for it.